The Visitation is the fourth serial of the 19th season of Doctor Who. Though it was fourth one aired, it was actually the second one produced, and thus only the second time Peter Davison played the titular character (he briefly appeared in the final episode of the 18th season but only at the end so that viewers could get a hint of what the new Doctor looked like). The episode was written by Eric Saward and this was his first time writing for the series. Given the newness for both actor and writer The Visitation has something of an unfinished quality about it.
Tiring of traveling with the Doctor, Tegan has demanded to be taken home. The Doctor agrees and even promised to drop her off at Heathrow only 30 minutes from the time she left so that she can begin her job as a stewardess for Australian Air. Par for the course when the Doctor tries to land the TARDIS at a specific place in a specific time, he gets it only half right. They land where Heathrow should be but some 300 years too soon.
Never one to let a mistake get in the way of an adventure, the Doctor, Tegan, and his other two companions - Adric and Nyssa - take off to see what's going on. After hiking for a little bit, they are attacked by a group of villagers who fear these strangers may have the plague. Disoriented from burning sulfur (something suspected to ward off the plague), our heroes lose their way and cannot find the TARDIS. The Doctor getting lost was one of the first ways they showed that this new Doctor is not going to be the surefooted man that Tom Baker's Doctor was.
They run into Richard Mace, an eccentric thespian and sometimes highwayman who takes them to safety in an abandoned barn. There, the Doctor notices an alien necklace on Mace and when questioned he notes that there was a comet that landed nearby recently. Knowing this was surely the alien craft crash landing, the Doctor and his companions begin a more thorough search of the surrounding area. They come to an old manor where they find more clues to the alien visit including a holographic wall and eventually a masked android who stuns Tegan and Adric with a ray gun while the Doctor, Nyssa, and Mace escape.
Tegan and Adric are bound to a table and questioned about the Doctor by a Terileptil (which from the bad rubber suit is some kind of giant lizardy turtle thing that walks on two legs and speaks perfect English.) Turns out he (and two others whom we barely see) are prison escapees looking for a new home and Earth seems just the place (after they destroy all the humans with plague-covered rats.)
The Doctor and Mace then go to question the miller, who seems to come and go as he pleases, but wind up getting captured, get the sonic screwdriver destroyed (it would not be seen again until 1996), and are nearly killed by the plague carrying rats. The Doctor, of course, saves the day and everybody heads back to the TARDIS where they find that Nyssa has destroyed the android with a big vibrating sonic device. Everybody then heads into London to find the Terileptil headquarters where they engage in fisticuffs with the reptilian creates, kill them, and manage to start the Great Fire of London.
This was my first time with Davison. He's probably my least favorite of the ones I've seen (all the new ones plus Tom Baker and William Hartnell.) He isn't bad, but he seemed to be lost in exactly how he wanted his version to go. Given this is is second round playing the part, and that he had to follow the long-running and iconic Baker I'm willing to give him the benefit of the doubt and expect that he gets better at it. Thus I'll hold my judgement until I've seen more of him.
The three companions were not well drawn in this episode. Adric seems to exist for no other reason than to mope and whine, while Tegan mostly complains and yells at the Doctor for not fixing everything. Nyssa fares better and is actually given some personality, but she doesn't really stand out. The two villains are pretty standard Doctor Who baddies (though the android's disco get-up is unintentionally hilarious, and the Terileptil's rubber suit is nearly as bad - though as a side note it should be noted it contains the very first Doctor Who use of animatronics which make his gills move.) The real stand-out of the episode is Richard Mace, who is played (or should I said over-played) with great gusto by Michael Robbins. He chews his scenes then spits them right back out.
I suspect the problem with the characters is that there are simply too many of them for anyone to be fully fleshed out. With three companions, two villains, Richard Mace, and an assortment of villagers, there are so many people taking up screen time that no one has a chance to stand-out.
As per usual, the DVD of The Visitation is loaded with extras. There's an audio commentary with the main actors and the director of the episode. There are numerous featurettes on the making of the episode, on the television studio where Doctor Who was created, on the music, etc. There is a fun little documentary where the Doctor and his companions revisit the forest and old manor area and reminisce about the episode. There's an interview with director Peter Moffatt, production notes, and some outtakes.